Magnetism and spin-driven ferroelectricity in the multiferroic material α - Cu2V2O7.

The magnetic anisotropy, exchange couplings, and spin-driven ferroelectricity in recently discovered multiferroic oxide α - Cu2V2O7 have been investigated using first-principles calculation and symmetry analysis. Density functional theory (DFT) calculations predict easy a -axis anisotropy, while applying an on-site Hubbard correction (DFT + U) converts the easy axis into b direction. These results can explain the discrepancy of easy axis between previous theoretical prediction and experimental results. The third-nearest-neighbor exchange interaction is proved to be dominant for the antiferromagnetic structure. The nearest-neighbor Dzyaloshinskii-Moriya interaction plays an important role in the origins of spin canting, and the canted magnetic moments are oriented predominantly along the c axis. Although the spin-dependent p - d hybridization mechanism induces a sizable electric polarization, the observed large polarization can be mainly attributed to the exchange-striction mechanism including spin-lattice coupling. [ABSTRACT FROM AUTHOR]